In geometry, the triakis truncated tetrahedron is a convex polyhedron made from 4 hexagons and 12 isosceles triangles.

It can be used to tessellate three-dimensional space, making the triakis truncated tetrahedral honeycomb.

[1][2] The triakis truncated tetrahedron is the shape of the Voronoi cell of the carbon atoms in diamond, which lie on the diamond cubic crystal structure.

[3][4] As the Voronoi cell of a symmetric space pattern, it is a plesiohedron.

[5] For space-filling, the triakis truncated tetrahedron can be constructed as follows: